<!DOCTYPE html>
<html lang="zh-CN">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>

<body>
    <script>
        // 第一题 输出年龄
        let arr = [4, 17, 56, 89, 67]
        // for (let i = 0; i < arr.length; i++) {
        //     if (arr[i] > 18) {
        //         document.write(`${arr[i]}`)
        //     }
        //     document.write(`<br>`)
        // }

        //第二题  求总和
        // let sum = 0
        // for (let i = 0; i < arr.length; i++) {
        //     sum = sum + arr[i]
        // }
        // document.write(`${sum}`)

        //第三题
        // let sum = 0
        // for (let i = 0; i < arr.length; i++) {
        //     sum = sum + arr[i]
        // }
        // document.write(`${sum / 5}`)

        //第四题  求最大值
        //需要声明一下max的值
        let max = arr[0]
        for (let i = 0; i < arr.length; i++) {
            if (arr[i] > max) {
                max = arr[i]
            }
        }
        document.write(`${max}`)
    </script>
</body>

</html>